I really like the custom Prodigy Apex 2.5 Tim at Enlightened Equipment made me. Might hit him up for some ideas or to have him make you one. It's what I'd call a 45-47*F quilt made with 15D-WR outside, 10D inside 6'/Wide and comes in at 13.5oz.

I really like my "summer" quilt that Tim made me. It uses 2.5 Climashield Apex and the old M50. It is 76" long, 53" wide at the head and has a straight taper down to 39.5" at the foot and weighs 11.5 oz! I absolutely love it as my summer quilt!

I also have a 6' long, WIDE 35 F Prodigy quilt and it is great too. It has the 15D WR outer and the 10D inner and comes in at 18.2 oz. I actually pushed it to 25 F last weekend by supplementing it with a pair of down pants, socks and a parka. This was under my GoLite Poncho tarp pitched in a half pyramid.

I really like the idea of synthetic quilts for temps above 35 F or so. For me, it just makes sense...

I also like that the Climashield Apex quilts don't use the sewn thru construction to create baffles like down needs. Instead, it is simply sewn around the perimeter, which means there are no spots for even a little bit of cold to seep in...

You're right. Colder than 35-40* down is the clear winner. However above this point small amounts of down are harder to control and the weight advantage is much less as less insulation is required. I like synthetic for summer and down the rest of the time. Also a 45* APEX bag works better at 85-90* than a down bag as my sweat is much less an issue. No matter how warm it is I can't sleep uncovered so APEX is my summer choice. My wife uses a 20* Revelation on 75* nights so clearly everyone is differant.

I sewed my quilt (first thing i've sewn on a machine since Home Ec) for around the cost of the down needed to make a 30-40*

it is not always the walking in the rain that can get your bag wet. OP is doing the Long Trail this summer i believe. Shelters can leak, wind can blow rain in, YOU can be wet, tent can be wet from you being wet, stuff spills etc.

my shoulder season quilt is RevX 20 because advantages go that way for colder.

I got a good bit of info from Jake before I went and did the northern LT this past September (Maine Jct. to Journeys End in 11 days (including travel days, with the coldest night being a humid 30* and frost almost hanging in the air) and used my 30* Western Mountaineering Megalite. For SUMMER I'd for sure bring my MYOG 2.5 Apex quilt - - since WET is a bit factor on that trail, and since you can always layer up under the quilt for added warmth on a random cool evening. I'm good to 40* with a light baselayer (or just wearing my wind jacket and wind pants) with my 14 oz. CS Apex 2.5 Quilt (so easy to make you could even just whip stitch it by hand all around 4 sides). Just my 2 cents.

The Marmot Cloudbreak 30 is slightly warmer than I was looking for, but the price and weight are right! Sadly, it looks like I can only find it in a "regular" and at 6'2", I need a long.

I found this little gem. it weighs in at 1lb 12oz, which for a 55º bag seems like a bit much, but it's only $80! That might sell me. I feel like at 55º, my clothing might even be enough... but I'm sure this bag will be warm enough for summer summits in the northeast as long as I don't do like, Mt. Washington.

TNF also makes a 45º one for a couple more ounces, but I'd probably stick to the 55º personally.

And yeah, Synthetic VS Down, I like down in the winter when I need to carry around a whole bunch of it, but I've been generally pleased with Synthetic everywhere. I'll go for a down jacket as part of my sleep system but all my sleeping bags are synthetic, because high winds DO blow rain into my hammock and I DO fall into rivers sometimes...

"I feel like at 55º, my clothing might even be enough... but I'm sure this bag will be warm enough for summer summits in the northeast ..."

Max,

I've been backpacking northeast summits for many years, and would never go out with a bag not rated at least to freezing. At the freezing point, you can rely on the insulating clothing to keep warm. If you're doing the LT, as suggested by another poster, it can get very wet also. It runs right through a snow belt, and summer rains can go for many days on end. The shelters on the LT won't add much warmth, but at least get you out of the rain with lots of space to cook etc. In my experience, the northern sections tended to be rainier than the southern, absolutely no idea why.

As to your question, I think the EMS Velocity, with PrimaLoft fill and a Pertex Qauntum shell, is as good a synthetic bag as you'll find without paying a premium price. I was hoping your thread might bring out something as good and lighter, though. Or perhaps, you may try the other posters' suggestions to use a quilt.

Best wishes for a great backpack, and please don't totally rule out The Cohos Trail.It's not quite as rainy, is a lot less crowded, has some great lodges along the way (if you can afford lodging - around the same prices as motels, and often there are discounts for hikers), and some truly off the beaten path locations, like the Baldhead shelter, one of three north of the National Forest to the Canadian border.Disclosure: I am affiliated with The Cohos Trail Association (volunteer work only).